The present invention regards a plant for unloading stacks of thermoformed products from a stack receiving cage onto a removing conveyer.
With the expression xe2x80x9cthermoformed objectsxe2x80x9d in this description and in the claims, it is meant hollow packaging products, typically, lids and containers, e.g. drinking cups, coffee cups, dessert cups, tubs, plates, trays and the like.
Unloading and handling in general of a plurality of stacks of thermoformed objects is often problematical as the passage from one transfer support to another needs constant surveillance to ensure the perfect axial alignment of the stacks and it is necessary that the various products forming each stack are kept compact to avoid the disintegration of the stacks, which may occur for example with shallow containers, such as lids and plates, which can be a source of problems and difficulties in successive handling operations, e.g. during the de-stacking of these products, for example in an automatic de-stacking machine.
The main object of the present invention is to provide a plant for unloading or discharging a plurality of parallel stacks of thermoformed products from a containing crate or cage to another support, which makes it possible to change the orientation direction of the stacks, whilst keeping these compact and in perfect axial arrangement.
Another object of the present invention is that the said unloading plant or system permits the graduated and sequential discharge of a pre-established number of stacks at a time until all the stacks in a containing cage have been discharged.
Yet another object of the present invention is that the said discharge plant is of a high efficiency and can operate in step and in synchronisation with a thermoformed products stacking line downstream of a single station thermoforming machine or press with form and cut mould.
These and other objects, which will be better appear below, are attained by a plant for unloading stacks of thermoformed products starting from a stack containing case, which includes a support structure, at least one supporting plate for a respective stack containing cage, that is mounted for rotation on said support structure, drive means arranged to cause the said support plate to effect angular excursions of predetermined amplitude around a horizontal axis, thereby angularly moving a respective stack containing cage between an erect position, in which the stacks of thermoformed objects contained therein extend in a substantially vertical direction, and an inclined discharge position, expeller means for expelling stacks of thermoformed products from said support plate when said support plate is in an inclined discharge position, a receiving conveyer for the stacks of thermoformed products unloaded from said containing cage located downstream of the discharging position of said support plate, and drive means arranged to vertically move the said support plate between a plurality of unloading positions to unload stacks of thermoformed objects at different levels onto said receiving conveyer.
Advantageously, the plant includes drive means to vertically move said support plate between a plurality of discharge positions to unload groups of stacks of thermoformed objects onto said receiving conveyer at different levels. Moreover, said receiving conveyer is inclinable substantially at the same angle of inclination as said support plate in its inclined discharge position.